Current climate control systems in automobiles utilize a heater core to heat air that is directed into the cabin of the automobile to provide interior heating. The heater core is typically heated by circulating engine coolant from the engine through the heater core. (Coolant being a term relative to the engine temperature, as the coolant is used to “cool” the engine of the automobile, which is how the coolant obtains the thermal energy used to heat the air passing through the heater core, and thus the coolant is at a high temperature relative to atmospheric temperatures). Typically, the rate of coolant flow through the heater core is governed by various parameters relating to the engine and/or automobile operation and/or coolant pump operation. By way of example, the rate of flow through the heater core may be directly related to engine RPM; the higher the RPM, the higher the coolant flow rate through the heater core. Still further, it may be related to the speed of a coolant pump. Alternatively or in addition to this, the rate of flow of coolant through the heater core may be related to the temperature of the engine. That is, for example, the rate of coolant flow may increase as the temperature of the engine increases. Indeed, in some designs for automobiles, coolant only circulates through the engine (and thus the heater core) when the temperature of the engine has reached a predetermined value. Thus, the rate of flow through the heater core of coolant is variable and controlled by parameters that are not directly related to the required heat output of the heater core. This is sometimes a problem, because by controlling the flow rate of coolant through the heater core solely based on engine parameters, the true need to achieve a minimum circulation rate through the heater core, which may be needed to ensure that the climate control system can provide hot air at an adequate temperature and at an adequate mass flow rate to the cabin, is ignored. Therefore, in some situations, the coolant flow rate may be too low to sufficiently heat the air being directed into the cabin so that the occupants of the cabin will feel comfortable. This is especially the case in situations of extremely cold ambient weather at low engine speeds and/or low coolant pump speeds (and thus low coolant flow rates).
Thus, low coolant flow rate may be a problem because, depending on the ambient temperatures and/or the increase in room temperature that the cabin occupants desire, the heater core may not be able to heat the air being directed into the cabin sufficiently for the occupants to feel comfortable.
One possible solution to the problem of low coolant flow at low engine speeds/low coolant pump speeds might be to simply maintain the flow of coolant through the engine, and thus the heater core, at a higher flow rate. However, this may result in a reduction in fuel efficiency as well as increased wear and tear on automobile components (e.g., a water pump that now must run twice as fast), thus making the automobile less economical, less environmentally friendly and more maintenance intensive.
Therefore, there is a need to better control the flow of coolant through the heater core to better ensure that the heater core is able to provide enough heated air to the cabin of an automobile so that occupants in the cabin feel comfortable, even at extremely cold and low engine/pump speed conditions, in a manner that provides for economical operation of the automobile in both the short and/or long term.